High pressure sand and asphaltene trap

ABSTRACT

A high pressure trap for separating sand and asphaltene from a high pressure stream of oil includes a vessel having a longitudinal axis arranged substantially vertically; an oil inlet for introducing a high pressure stream of oil with entrained sand and asphaltene into the vessel; an impact plate in the vessel and arranged at the inlet so that the high pressure stream of oil impacts the plate such that the entrained sand and asphaltene separate from the stream and collect in a bottom portion of the vessel; and a chemical inlet at the bottom portion for introducing chemicals to contact separated sand and asphaltene in the bottom portion to facilitate removal of the separated sand and apshaltene from the vessel.

BACKGROUND OF THE INVENTION

The invention relates to a high pressure separator or trap for separating sand and asphaltene from a high pressure stream of oil.

Much of the hydrocarbon reserves in Venezuela and other locations have a relatively large content of asphaltene which, if not addressed, can cause significant issues with respect to plugging of flow lines and equipment, inefficient flow properties and the like.

Various approaches are known for treating the crude oil, once it is produced, at facilities for removing or converting the asphaltene. Problems remain, however, with respect to flow of the produced crude oil from the well head to the facility for treatment and removal of asphaltenes.

It is therefore to be appreciated that an improvement in handling of sand and asphaltene in produced hydrocarbon streams is desirable.

SUMMARY OF THE INVENTION

In accordance with the present invention, a high pressure trap and separator is provided which allows for separation of sand and asphaltene from a stream of hydrocarbons at a very high pressure, for example, immediately after being produced from the well and prior to feeding to other surface flow equipment such as the shock box, which is a device for optimizing the flow of production flow in wells, and for optimizing the differential pressure to have less production of sand. This allows for efficient separation and removal of sand and asphaltene before the produced hydrocarbon is transported to facilities for further processing.

In accordance with the present invention, a high pressure trap for separating sand and asphaltene from a high pressure stream of oil is therefore provided, which comprises a vessel having a longitudinal axis arranged substantially vertically; an oil inlet for introducing a high pressure stream of oil with entrained sand and asphaltene into the vessel; an impact plate in the vessel and arranged at the inlet so that the high pressure stream of oil impacts the plate such that the entrained sand and asphaltene separate from the stream and collect in a bottom portion of the vessel; and a chemical inlet at the bottom portion for introducing chemicals to contact separated sand and asphaltene in the bottom portion to facilitate removal of the separated sand and apshaltene from the vessel.

In further accordance with the invention, a method for separating sand and asphaltene from a high pressure stream of oil is also provided, which comprises the steps of feeding a high pressure stream of oil to a high pressure trap for separating said sand and asphaltene entrained in the high pressure stream wherein the trap comprises a vessel having a longitudinal axis arranged substantially vertically; an oil inlet for introducing a high pressure stream of oil with entrained sand and asphaltene into the vessel; an impact plate in the vessel and arranged at the inlet so that the high pressure stream of oil impacts the plate such that the entrained sand and asphaltene separate from the stream and collect in a bottom portion of the vessel; and a chemical inlet at the bottom portion for introducing chemicals to contact separated sand and asphaltene in the bottom portion to facilitate removal of the separated sand and apshaltene from the vessel; whereby oil substantially free of entrained sand and asphaltene exits an oil outlet of the trap; injecting chemicals through the chemical inlet to treat asphaltenes collected in the bottom of the vessel; and removing sand and treated asphaltene from the bottom of the vessel.

Other objects, advantages and features will appear hereinbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed prescription of preferred embodiments follows, with reference to the attached drawings, wherein:

FIG. 1 is a side view of a high pressure trap in accordance with the present invention;

FIG. 2 is a sectional view of a trap in accordance with the invention;

FIG. 3 is a still further sectional view of the lower portion of the trap in accordance with the present invention; and

FIG. 4 schematically illustrates particle or sediment flow through a trap in accordance with the present invention.

DETAILED DESCRIPTION

The invention relates to a high pressure trap for separating sand and asphaltene from a high pressure stream of oil. FIG. 1 shows such a trap 10, in the form of a generally vertically elongate vessel 12 having a longitudinal axis X (FIG. 2) which is arranged substantially vertically. Vessel 12 may be substantially cylindrical in shape, and has an oil inlet 14 through which a high pressure stream of oil with entrained sand and asphaltene is introduced into vessel 12. As will be further discussed herein, trap 10 serves to separate the entrained sand and asphaltene from the high pressure stream of oil before the stream of oil is passed to other surface equipment for upgrading, processing, transportation and the like. In this way, advantageously, plugging problems in all this surface equipment which are typically caused by the asphaltene are reduced and/or completely avoided.

Still referring to FIG. 1, vessel 12 also has an outlet 16 through which oil is removed from vessel 12 after sand and asphaltene have been separated therefrom. Thus, from oil outlet 16, the oil can be passed to the other surface facilities as discussed above, without carrying along the entrained sand and asphaltene.

Referring also to FIG. 2, a skirt 18 and base 20 extend from a lower end 22 of vessel 12 for supporting vessel 12 in an upright or substantially vertical position. Skirt 18 and base 20 also advantageously elevate the lower end 22 of vessel 12 to provide easier access to this portion of vessel 12 as this is the area where sand and asphaltene are collected from within vessel 12, and is the area where such materials are removed from vessel 12, through outlets or unloading ports 2426.

FIG. 3 shows outlet 24, which also functions as a chemical injection inlet, through which various chemicals such as solvents and the like are introduced into lower end 22 of vessel 12 to treat asphaltene collected therein and facilitate removal of the asphaltene and separated sand from vessel 12.

FIG. 2 shows an internal impact plate 28 which is positioned relative to oil inlet 14 so that the high pressure stream of oil entering vessel 12 from inlet 14 impacts plate 28. This impact causes the heavier components of the stream of oil, particularly the sand and asphaltene, to sink to the lower end 22 of vessel 12 as illustrated in FIG. 4. The majority of the particles collect as sediment in the bottom of vessel 12. Only a minimum of such components continues with the fluid circulation.

These materials can form agglomerates, and would otherwise plug any type of transportation or processing facility to which the stream of oil is transferred. In accordance with the present invention, oil from oil inlet 14 impacts plate 28 such that sand and asphaltene separate from the flow and collect in the lower end 22 of vessel 12 while oil which is now substantially free of these entrained materials passes around impact plate 28 and eventually exits vessel 12 through outlet 16.

As best illustrated in FIG. 2, impact plate 28 preferably extends downwardly from an inner surface of the upper end 30 of vessel 12, and extends downwardly toward lower end 22 such that it is positioned between oil inlet 14 and oil outlet 16. Preferably, plate 28 extends downwardly for a substantial portion of the longitudinal length or height of vessel 12, for example greater than 50% of the vertical height of vessel 12. This helps to assure substantial separation of sand and asphaltene from the oil due to impact with plate 28.

As shown also in FIGS. 2 and 3, lower end 22 of vessel 12 preferably has an inner surface 23 which is concave in shape facing inwardly, toward the interior of vessel 12.

Furthermore, as shown in FIGS. 2 and 3, the outlet that also serves as input for chemical injection and the outlet 26 can be joined and connected with the lower end 22 substantially in a radial center of the lower end 22 through a sealable tube 27. Asphaltenes and sand can be removed through the outlets 24 and 26 after asphaltenes are treated with chemicals through chemical injection through inlet 24.

Base 20 should be sized sufficiently to provide stability for trap 10, taking into account the weight of fluids and forces to be exerted on plate 28, in accordance with the invention.

The chemical to be injected into outlet 24 during chemical injection is a dispersant of asphaltenes. The dispersant can be a solution of one or more surfactants, dissolved in a solvent such as a hydrocarbonate of aromatic character. The solvent promotes the dissolution of the asphaltene already precipitated through physico-chemical mechanisms of dispersing agents, and there is preferably no transformation of asphaltenes on-site, only removal of asphaltenes, followed by the disposal through any mechanism that may be desired.

Vessel 12 may preferably be designed to withstand internal pressures of at least about 5,000 psi and a typical high pressure stream of oil may be fed to vessel 12 at a pressure of between about 1500 and about 5200 psi, for example, about 3,200 psi, which is the pressure of a well where the apparatus of the invention may typically be used.

It should be appreciated that trap 10 according to the invention can advantageously be used by passing a produced stream of hydrocarbons with entrained asphaltenes and other undesirable particulates through the trap. The lower portion of the trap can either be continuously treated with asphaltene solvent to remove same from the vessel, or the lower portion can be monitored to determine when it is appropriate to remove accumulated materials from the vessel, at which time the lower portion of the vessel can be periodically treated with chemicals such as asphaltene solvent for removal of same.

It is to be understood that the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention, and which are susceptible of modification of form, size, arrangement of parts and details of operation. The invention rather is intended to encompass all such modifications which are within its spirit and scope as defined by the claims. 

1. A high pressure trap for separating sand and asphaltene from a high pressure stream of oil, comprising: a vessel having a longitudinal axis arranged substantially vertically; an oil inlet for introducing a high pressure stream of oil with entrained sand and asphaltene into the vessel; an impact plate in the vessel and arranged at the inlet so that the high pressure stream of oil impacts the plate such that the entrained sand and asphaltene separate from the stream and collect in a bottom portion of the vessel; and a chemical inlet at the bottom portion for introducing chemicals to contact separated sand and asphaltene in the bottom portion to facilitate removal of the separated sand and apshaltene from the vessel.
 2. The apparatus of claim 1, wherein the vessel comprises a substantially cylindrical vessel and the longitudinal axis is a central axis of the cylindrical vessel.
 3. The apparatus of claim 1, wherein the bottom portion is substantially concave facing inward in the vessel.
 4. The apparatus of claim 1, wherein the inlet is positioned in an upper portion of the vessel.
 5. The apparatus of claim 4, further comprising an outlet for separated oil, wherein the outlet is positioned in the upper portion of the vessel.
 6. The apparatus of claim 5, further comprising an outlet for separated sand and asphaltene at the bottom portion of the vessel.
 7. The apparatus of claim 6, wherein the impact plate extends downwardly from an upper inner surface of the vessel, past the oil inlet and toward the outlet for separated sand and asphaltene.
 8. The apparatus of claim 7, wherein the impact plate is between the oil inlet and the outlet for separated oil.
 9. The apparatus of claim 1, further comprising a skirt extending downwardly from the vessel and a base at a lower end of the skirt for supporting the vessel.
 10. The apparatus of claim 9, wherein a conduit is communicated with the chemical inlet and extends laterally from inside the skirt to outside the skirt through an opening in the skirt.
 11. The apparatus of claim 10, further comprising an additional opening in the skirt to allow access to the bottom of the vessel and the chemical inlet.
 12. A method for separating sand and asphaltene from a high pressure stream of oil, comprising the steps of: feeding a high pressure stream of oil to a high pressure trap for separating sand and asphaltene entrained in the high pressure stream wherein the trap comprises: a vessel having a longitudinal axis arranged substantially vertically; an oil inlet for introducing a high pressure stream of oil with entrained sand and asphaltene into the vessel; an impact plate in the vessel and arranged at the inlet so that the high pressure stream of oil impacts the plate such that the entrained sand and asphaltene separate from the stream and collect in a bottom portion of the vessel; and a chemical inlet at the bottom portion for introducing chemicals to contact separated sand and asphaltene in the bottom portion to facilitate removal of the separated sand and apshaltene from the vessel; whereby oil substantially free of entrained sand and asphaltene exits an oil outlet of the trap; and injecting chemicals through the chemical inlet to treat asphaltenes collected in the bottom of the vessel; and removing sand and treated asphaltene from the bottom of the vessel.
 13. The method of claim 12, wherein the injecting and removing steps are carried out continuously.
 14. The method of claim 12, further comprising the step of monitoring the bottom of the vessel and, when asphaltenes in the bottom of the vessel reach a predetermined level, carrying out the injecting and removing steps. 